Opperman began his competitive life in boxing and football before moving to motorcycles on the American Motorcycle Association Pacific Coast circuit. He progressed to midget cars in the Bay Cities Racing Association and became a sprint car regular in 1967. He earned the title of one of the "Original Outlaws" due to his preference for traveling the country to chase lucrative races rather than competing for points within a single sanctioning body. In 1968, Jerry Janssen of Speedway Motors discovered him in California racing a car powered by a Ranger airplane engine and brought him to Lincoln, Nebraska, to further his career.
His success was prolific; in 1970, he won his first time out at both Selinsgrove and Williams Grove. In 1971, he won the Knoxville Nationals and the Western World Championship. His most dominant season came in 1972, when he won a staggering 44 of 90 main events. Opperman was also a two-time National Supermodified champion (1971–1972) and the 1973 World Dirt Track champion. In 1976, he secured a major victory at the Hulman Classic in Terre Haute.
Opperman's natural ability caught the attention of racing legends A.J. Foyt and Parnelli Jones. He made nine starts in the USAC Championship Car series between 1974 and 1976, recording three top-ten finishes. His first Indianapolis 500 start in 1974 was with a team co-owned by Jones, where he finished 21st. He returned in 1976 to finish 16th. Beyond open-wheel racing, he also competed in NASCAR, finishing eighth at Pocono Raceway in 1974.
Opperman was known for his distinctive appearance, featuring long hair, ragged blue jeans, and a battered western hat that belonged to his brother, Jay, who died racing at Knoxville Raceway in 1970. Though associated with the drug culture early in his career, he became a dynamic Christian while living in Beaver Crossing, Nebraska. He often displayed a cross on his helmet and cars and worked toward establishing a ranch in Montana for troubled youth.
His career was effectively ended by two major accidents. In September 1976, while battling for the lead at the Hoosier Hundred at the Indianapolis State Fairgrounds, he suffered critical head injuries. After missing the 1977 season, he returned to the outlaw circuit in 1978 but could not replicate his former success. A second accident in 1981 at Jennerstown left him disabled and requiring constant medical care until his death in 1997 in Fountain, Florida.
Opperman was an inaugural inductee into the National Sprint Car Hall of Fame in 1990. He was posthumously inducted into the International Motorsports Hall of Fame in Talladega, Alabama, in 2011.
This article is based solely on the supplied corpus. No external sources were consulted; claims that could not be substantiated against the corpus were omitted under the drop-the-claim rule.